astrological vs impenetrable

astrological

adj
  • Of, or relating to astrology. 

impenetrable

adj
  • Opaque; obscure; not translucent or transparent. 

  • Not penetrable. 

  • Incomprehensible; fathomless; inscrutable. 

noun
  • A person not openly given to friendship. 

How often have the words astrological and impenetrable occurred in a corpus of books? (source: Google Ngram Viewer )